Hours after releasing Portal 2 on Steam, creator Valve has announced predecessor Portal has sold close to four million units.
But Portal has likely sold substantially more copies. As GameSpot reports, the four million figure excludes digital download sales from Steam.
Portal launched in 2007 as part of the superb The Orange Box compilation.
In 2008 it launched as a standalone retail product. In the same year a version called Portal: Still Alive launched on Xbox Live Arcade.
Eurogamer's Portal review turned up a 9/10. "And so we're left with a curious contradiction: one of the most interesting and delightful things Valve's ever done, but also one of its least fulfilling," wrote Tom.
Thankfully, the sequel went one better. Eurogamer's Portal 2 review has all the details.